Elevator



UNITED sTATEs APATENT orricn OTIS TUF'IS, ORBOSTON, MASSACHUSETTS.

ELEVATOR.

Specification of Letters Patent No. 32,441, dated May 28, 1861.

To all whom it may concern.'

Be it known that I, Oris TUrTs, of Boston, county of Suffolk, and Stateof Massachusetts, `mechanical engineer, have invented certain new anduseful Improvements in Elevators or Hoisting-Machines; and I declarethat the following description and the accompanying drawings form afull, clear, and exact specification thereof.

The accompanying drawings represent a machine, embracing` my presentimprove-` ments and are referred to, by figures and letters in thisspecification.

Figure 1, is atop view. Fig. 2, is a vertical section, on line A. BrefFig. 1. Fig. 3, is a front view of a portion of the machine, some of theobscured parts being representedby dotted lines. Fig. 4, is alongitudinal section of the hoisting drum,-- on line C. D. of Fig. 1.

`although `I have long maintained the superior safety of methods ofelevating based on principles of fixed and rigid supports, as peculiarlyembodied in my vertical railway elevator, patented, Aug. 9th, 1859 overthe principle of suspensiom on which, as far as I am acquainted, allother elevators are constructed. Yet, inasmuch, as suspension elevators,from their simplicity and economy, must probably, long, and perhapsalways occupy a large field in the public use, I have therefore turnedmy attention to methods, `whereby their utility, convenA ience andeconomy, and more especially their safety may be greatly enhanced. Inall elevators of this class known to me, the weight, or car, issuspended by a single rope or cha-in the` estimated strength of which,though it may be largely beyond the weight to be suspended, it is yetliable to give way from accidents or causes, sometimes the mostincalculable and paradoxical. And it is a well known fact, that ropes orchains, which have carried far greater weights, hundreds of times overthe same heights` have sometimes given way, under what was deemed veryinferior loads, and in many instances the most ,disastrous consequenceshave been experienced.` Such is the great and appalling risk ofdepending upon a single rope or chain, for an elevator, especially whenpersons are to be carriedwhatever may be the comparative strength of theropeor chain, in proportion to the weight suspended. In such machines itis usual to load the rope or chain, to an amount `breaking weight.

not exceeding one third of its estimated In my improved machine, todiminish the chances of breaking to the degree of almost certain safety,instead of one hoisting rope, or chain I make use of a series of suchropes or chains (64,) two, four, six, eight, ten, or even more innumber, each of which, is independently attached, to the hoisting car(2),) and also after passing up, over the roller (0,) to the hoistingbarrel or drum (cl,) `on which they simultaneously wind, either of whichropes or chains being sufiicient to sustain the load put upon themachinewith the usual margin to spare. I have resorted to theconsideration of different formulas and theories, to estimate theircomparative safety as compared with a single rope or chain, and in mycaveat,

Vbut further investigation and consideration has convinced me, that eventhat, was far too low an estimate of the comparative safety, acquired byadditional independent supports. The truth being that it is a compoundratio between the chance of accident happening to any particular rope,on any particular trip of the machine, or in any particular space oftime, and the chance of its simultaneously happening to the entireseries in the same space of time, which will give a greatly increasedratio of comparative safety beyond what I then stated. Norare theseadvantages at all to be obtained by using one rope or chain of largersize, as might appear at first. view, for in case `of a chain the chanceof accident is in al flaw, or other imperfection, which may pertain to asingle one, of whatever size, and in ropes, and particularly wire ropes,which are now mostly used-one of eXtra large size, ismuch more weakenedby frequent bending over sheaves and drums, on account of the dierentlengths of the outside and inside of the ropes, besides that the strandsbeing all combined andas it were, blended in to one structure, thechance of accident or uncalculated imperfections, does in a degreepertain to a rope as to a chain.

I furthermore arrange in combination with the series of ropesor chains,above described, a series of levers or balances, so

that while the principle of independent attachment of each rope or chainis maintained, the weight or strain is equalized on each rope or chain.The manner in which I accomplish these objects, and make the machineperfectly self adjusting is by attaching the end next the car of eachrope or chain (0,) to a lever, or steel-yard beam (6,) the short arm ofwhich, is fixed in a standard on the top of the car, while the longer orextended arm, is attached to a connecting rod (g,) which extends down,and takes hold of a spiral spring (7L) which is coiled within thetubular cylinder (2,) to the lower end of which, is fixed, the sheave(j,). On the top of the car, are also fixed the sheaves or rollers (70,)and the cord or chain (Z,) being firmly secured at each end, to somestationary part of the car, is inserted or woven under the sheaves (7c)and over the sheaves (y',) and is left with some slack as it is termed.All of which is shown by dotted lines in Fig. 3. And the operationclearly appears, that by the slack of the cord or chain (Z,) through thecombined mechanism, just described, enables the machine to accommodateor adjust itself to any inequality in the lengths of the hoisting ropes(00,) and should one of the hoisting ropes break, the rope, or chain(Z,) immediately draws tight across the space occupied by the sheaveconnected with the broken rope and the strain is at once, equallydistributed on the remaining ropes; the scales at once indicate theincreased strain on each rope, and the whole machine performs its oiiiceas before.

The spiral springs (la) being combined as described and represented, andaccurately constructed, also form a complete system of spring balance,indicating by the index point (m) and the scale (71,) both the equalityand the amount of strain, upon the hoisting ropes, or chains (a,) whichprinciple may also be availed of, when required, as a perfect set ofscales to note the weight of all or any articles, carried on theelevator. It must further beobserved that the spiral spring (h,) andtube may be wholly dispensed with, and the sheave (y',) inserteddirectly in the lower end of the connecting rod (g,) and still themachine perfectly perform its oflice of adjusting the strain equally onthe suspension ropes. The spring balances, described being merely toindicate the equality and amount of strain on each. Should the cord, orchain (Z,) give way from anycausewhich however is not likely to occur,on account off the limited amount of strain brought upon it, the levers(6,) would merely rise up till they struck the safety cross bar (0,) andno further accident or evil consequences, can ensue to the machine.

I do not confine myself to the precise method herein described, ofeffecting the automatic adjustment of the strain upon the hoistingropes, as I sometimes accomplish the' same by a rocking lever when tworopes are used, or by a system of such levers, when a greater number isused, or it may be accomplished in a degree, by springs attached eitherto the car, or the hoisting drum, or some intermediate point, in therope or chain.

By inspection of the sectional view of the hoisting drum, in Figs. l and2, the peculiar manner in which I construct the hoisting drums ofelevators or hoisting machines, will be observed. The cylindrical shellof the drum, being strengthened by the interior stays, or ribs (g,) andthe projecting gudgeons, or bearings (73) being cast with the rest ofthe drum, whereby economy of construction is greatly promoted, and aseparate shaft, that is wedged or otherwise fastened in to the drum maybe dispensed with; and the power is applied in any convenient manner tothe periphery of the hoisting drum itself.

In the machine represented in the drawings accompanying herewith, thehoisting drumis actuated by one of my voluted disks (s).

Claimsl. Constructing an elevator or hoisting apparatus, with a seriesof two or more hoisting ropes or chains, having independent attachments,and winding simultaneously upon the hoisting drum, for greater safety,substantially as described.

2. Equalizing the strain upon the series of ropes or chains of myimproved elevator, or hoisting machine, by automatic adjustment,substantially as described.

3. In combination with the hoisting apparatus, the spring balances forindicating the strain upon the series of ropes or chains employed,substantially as described.

OTIS TUFTS.

Witnesses:

LUTHER BRrGGs, J r., BENJAMIN P. CHANDLER.

